The class of polymers of carbon monoxide and olefin(s) has been known for a number of years. Brubaker, U.S. Pat. No. 2,495,286, produced such polymers of relatively low carbon monoxide content in the presence of free radical initiators, e.g., peroxy compounds. U.K. Patent specification No. 1,081,304 produces similar polymers of higher carbon monoxide content in the presence of alkylphosphine complexes of palladium salts as catalyst. Nozaki extended the reaction to produce linear alternating polymers in the presence of arylphosphine complexes of palladium moieties and certain inert solvents. See, for example, U.S. Pat. No. 3,694,412.
More recently, the class of linear alternating polymers of carbon monoxide and at least one ethylenically unsaturated hydrocarbon has become of greater interest in part because of the greater availability of the polymers. The more recent general process for the production of the linear alternating polymers is illustrated by a number of published European Patent Applications including Nos. 121,965, 181,014, 213,671 and 257,663. The process usually involves the use of a catalyst composition formed from a Group VIII metal selected from palladium, cobalt or nickel, the anion of a non-hydrohalogenic acid having a pKa below about 6, preferably below 2, and a bodentate ligand of phosphorus, arsenic or antimony.
The resulting polymers are relatively high molecular weight materials having established utility as premium thermoplastics in the production of shaped articles such as containers for food and drink by procedures which are conventionally employed with thermoplastics. Although the linear alternating polymers are crystalline with defined melting points, the polymers do tend to lose crystallinity when exposed to multiple melting/solidification cycles. This apparent loss of crystallinity results in decreases in certain of the desirable properties of the polymers. It would be of advantage to provide compositions of the linear alternating polymers which have been stabilized against such loss of crystallinity, i.e., which have a higher melt stability.